Epoxy resins containing thiadiazole and/or oxadiazole moieties

ABSTRACT

Epoxy resins containing more than one vicinal epoxide group per molecule and at least one thiadiazole, oxadiazole or both thiadiazole and oxadiazole moiety per molecule are disclosed, as well as curable and cured compositions thereof. Certain of these epoxy resins possess enantiotropic liquid crystallinity. These enantiotropic epoxy resins are useful in preparing copolymers with high glass transition temperatures and liquid crystalline morphology, which can result in enhanced unidirectional mechanical properties. These epoxy resins are useful in coating, casting, encapsulation, electronic or structural laminate or composite, filament winding or molding applications.

This is a continuation of application Ser. No. 08/119,781 filed Sep. 10,1993 now abandoned.

FIELD OF THE INVENTION

The present invention pertains to epoxy resins containing more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both thiadiazole and oxadiazole moiety per molecule,curable compositions and cured compositions thereof.

BACKGROUND OF THE INVENTION

A variety of compounds containing the thiadiazole and the oxadiazolemoiety have been prepared and characterized. Certain of these compoundshave been shown to be mesogenic (liquid crystalline). For example, B.Linstroem, et al, Ferroelectrics, volume 120, number 3-4,pages 225-230(1991) prepared a series of 2,5-(4-alkoxyphenyl)thiadiazoles andevaluated these liquid crystalline compounds for spontaneouspolarization versus molecular structure. N. K. Chudgar, et al, Mol.Cryst. Liq, Cryst., volume 172, pages 51-56 prepared a series of2-amino-5[4'-(4"-n-alkoxybenzoyl)phenyl]1,3,4-oxadiazoles andcharacterized the nematic liquid crystallinity exhibited by this seriesof compounds. T. A. Belousova, et al, Vysokomol, Soedin, Ser. B, volume33, number 5, pages 379-384 (1991) (Chemical Abstracts 115:185230j)characterized the occurrence of liquid crystallinity in fibers ofpoly(p-phenylene-1,3,4-oxadiazole). Epoxy resins containing thethiadiazole and/or oxadiazole moieties have heretofore not beenprepared. Likewise, the class of epoxy resins wherein said thiadiazoleand/or oxadiazole moieties are incorporated to form a mesogen haveheretofore not been prepared.

Mesogenic epoxy resins are an emerging new class of materials taught,for example by Earls, et al. in copending applications Ser. No.07/916,305 filed Jul. 17, 1992 now U.S. Pat. No. 5,270,404, Ser. No.07/916,293 filed Jul. 17, 1992, now U.S. Pat. No. 5,266,660 and Ser. No.07/919,677 filed Jul. 27, 1992, now U.S. Pat. No. 5,292,831. Thediglycidyl ethers of 4,4'-dihydroxy-alpha-methylstilbene,4,4'-dihydroxybenzanilide and 4'-hydroxyphenyl-4-hydroxybenzoatedisclosed in the Earls, et al. applications were characterized and shownto be monotropic nematic liquid crystals. Characterization of thediglycidyl ethers of 4,4'-dihydroxy-2,2'-dimethylazoxybenzene and4,4'-dihydroxybiphenyl revealed a lack of liquid crystallinity. Muller,et al, in U.S. Pat. No. 4,764,581 (Aug. 16, 1988) characterized thediglycidyl ether of 4'-hydroxyphenyl-4-hydroxybenzoate revealingmonotropic liquid crystallinity. In Hefner, Jr., et al., copendingapplications Ser. No. 07/905,592 filed Jun. 26, 1992, now abandoned andSer. No. 07/905,594 filed Jun. 26, 1992, now abandoned the diglycidylester of 4,4'-stilbenedicarboxylic acid was characterized and shown tobe a monotropic nematic liquid crystal. Characterization of thediglycidyl ester of 4,4'-dicarboxydiphenylazomethine revealed it to be amonotropic smectic liquid crystal, while the diglycidyl ester of4,4'-dicarboxychalcone revealed a lack of liquid crystallinity. InHefner, Jr., et al., copending application Ser. No. 07/890,735, nowpending, filed May 28, 1992, the diglycidyl amine ofN,N'-dimethyl-4,4'-diaminostilbene was characterized and shown to not beliquid crystalline. The majority of mesogenic epoxy resins which havebeen prepared and characterized exhibit monotropic liquid crystallinity.

Unexpectedly, certain of the mesogenic epoxy resin compositions of thepresent invention, notably the diglycidyl ethers of2,5-(4-hydroxyphenyl)thiadiazole and 2,5-(4-hydroxyphenyl)oxadiazolehave been shown to be enantiotropic liquid crystals, rather thanmonotropic liquid crystals. Copolymers prepared from mixtures containingthe aforementioned diglycidyl ethers possess high glass transitiontemperatures concurrent with liquid crystallinity. This liquidcrystalline morphology is susceptible to orientation during processing,for example as induced by shear or flow, which can result in enhancedunidirectional mechanical properties. This is not possible to any greatextent with conventional epoxy resins.

SUMMARY OF THE INVENTION

One aspect of the invention concerns epoxy resins containing an averageof more than one vicinal epoxide group per molecule and at least onethiadiazole, oxadiazole or both at least one thiadiazole and at leastone oxadiazole moiety per molecule.

Another aspect of the present invention concerns a blend comprising

(A) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(B) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule.

Another aspect of the present invention concerns the product of theadvancement reaction of

(A) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(B) at least one compound containing an average of more than onehydrogen atom per molecule reactive with a vicinal epoxide group; and

wherein component (A) and component (B) are present in an amount whichprovides a mole ratio of from about 0.01 to about 0.94 epoxide reactivehydrogen atoms in component (B) to epoxide groups in component (A).

Another aspect of the present invention concerns a curable blendcomprising.

(A) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(B) a curing amount of at least one suitable curing agent and/or curingcatalyst therefor.

Another aspect of the present invention concerns a curable blendcomprising

(A) a blend comprising

(1) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(2) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule, with

(B) a curing amount of at least one suitable curing agent and/or curingcatalyst therefor.

Another aspect of the present invention concerns a curable blendcomprising

(A) an advanced epoxy resin composition comprising the product of theadvancement reaction of

(1) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(2) at least one compound containing an average of more than onehydrogen atom per molecule reactive with a vicinal epoxide group,wherein component (2) and component (1) are present in an amount whichprovides a mole ratio of from about 0.01 to about 0.94 epoxide reactivehydrogen atoms in component (1) to epoxide groups in component (2), with

(B) a curing amount of at least one suitable curing agent and/or curingcatalyst therefor.

Another aspect of the present invention concerns the product or articleresulting from curing the aforementioned curable compositions.

Another aspect of the present invention concerns a phenoxy resincomposition comprising the product of the advancement reaction of

(A) at least one epoxy resin containing an average of more than onevicinal epoxide group per molecule and at least one thiadiazole,oxadiazole or both at least one thiadiazole and at least one oxadiazolemoiety per molecule, with

(B) at least one compound containing an average of more than onehydrogen atom per molecule reactive with a vicinal epoxide group,wherein component (A) and component (B) are present in an amount whichprovides a mole ratio of from about 0.95 to 1.05 epoxide reactivehydrogen atoms in component (B) to epoxide groups in component (A).

DETAILED DESCRIPTION OF THE INVENTION Compounds Containing Thiadiazole,Oxadiazole or both Thiadiazole and Oxadiazole Moieties

Typical of the compounds containing one or more thiadiazole, oxadiazoleor both thiadiazole and oxadiazole moieties used to prepare the epoxyresins which contain one or more thiadiazole, oxadiazole or boththiadiazole and oxadiazole moieties per molecule of the presentinvention include those represented by the Formula I

Formula I

    X--Ar--(X.sup.1).sub.n --Z--(X.sup.1).sub.n --(Ar--(X.sup.1).sub.n --Z--(X.sup.1).sub.n) .sub.n.sup.1 --Ar--X

wherein each X is independently a --OH, --SH, --NHR or --COOH group;each Z, is independently selected from the group consisting of a##STR1## each Ar is independently selected from the group consisting ofa ##STR2## each X¹ is independently a --O--, --S--, --SO--, --SO₂ --,--CO--, --O--CO--, --CO--O--, --S--CO--, --CO--S--, --NR--CO--,--CO--NR--, --NR--CO--NH--, --NH--CO--NR--, --NH--CO--O-- or--O--CO--NH-- group; each R is independently hydrogen or a hydrocarbylgroup having from one to about 10, preferably one to about 4, carbonatoms; each Y is independently --H, a hydrocarbyl or hydrocarbyloxygroup having from one to about. 10, preferably one to about 4,carbonatoms, a halogen atom, preferably chlorine, bromine or fluorine, a nitrogroup, a nitrile group, a --CO--R group or a --CO--OR group; A is adivalent hydrocarbyl group having from one to about 10, preferably fromone to about 4, carbon atoms and can also contain one or moreheteroatoms selected from N, O, and S; each n independently has a valueof zero or one and n¹ has a value of zero to about 10. The termhydrocarbyl as employed herein means any aliphatic, cycloaliphatic,aromatic, aryl substituted aliphatic or cycloaliphatic or aliphatic orcycloaliphatic substituted aromatic groups. The aliphatic orcycloaliphatic groups can be saturated or unsaturated. Likewise, theterm hydrocarbyloxy means a hydrocarbyl group having an oxygen linkagebetween it and the carbon atom to which it is attached.

Representative of the compounds containing one or more thiadiazole,oxadiazole or both thiadiazole and oxadiazole moieties include, forexample, 2,5-(4-hydroxyphenyl)thiadiazole,2,5-(4-hydroxyphenyl)oxadiazole, 2,5-(3-hydroxyphenyl)thiadiazole,2,5-(3-hydroxyphenyl)oxadiazole, 2,5-(2-hydroxyphenyl)thiadiazole,2,5-(2-hydroxyphenyl)oxadiazole,2,5-(3-cyano-4-hydroxyphenyl)thiadiazole,2,5(3-nitro-4-hydroxyphenyl)thiadiazole,2,5-(3-bromo-4-hydroxyphenyl)thiadiazole,2,5-(3-methyl-4-hydroxyphenyl)thiadiazole,2,5-(4-carboxyphenyl)thiadiazole, 2,5-(4-carboxyphenyl)oxadiazole,2,5-(4-mercaptophenyl)thiadiazole, 2,5-(4-mercaptophenyl)oxadiazole,2,5-(4-aminophenyl)thiadiazole, 2,5-(4-aminophenyl)oxadiazole,2,5-(4-N-methylaminophenyl)thiadiazole,2,5-(4-N-methylaminophenyl)-oxadiazole, ##STR3##

The compounds containing one or more thiadiazole, oxadiazole or boththiadiazole and oxadiasole moieties are prepared using well knownmethods. Thus the substituted 2,5-diaryl-1,3,4-thiadiazoles are preparedvia any of the following reactions:

(A) Treatment of substituted atomatic aldehydes with sulfur andhydrazine hydrate, typically in a 1:2:3 ratio, respectively underWillgerodt conditions from about 140° C. to about 180° C. for from about4 to about 24 hours, preferably at 150° C. for 12 hours. Solvents suchas ethanol, pyridine, dioxane, N,N-dimethylformamide are useful forconducting this reaction. This reaction proceeds through theintermediate benzalazine formed via reaction of one equivalent ofhydrazine with two equivalents of the aromatic aldehyde. The benzalazinemay be formed via reaction at temperatures below 150° C., for example byrefluxing in one of the aforementioned solvents for from 8 to about 96,preferably about 48 hours, isolated, and then later converted to thethiadiazole compound; or

(B) Treatment of thiadiazolidines with sulfur; or

(C) Cyclization of 1,2-dithiobenzoylhydrazines via removal of oneequivalent of hydrogen sulfide per equivalent of dithiobenzoylhydrazine;or

(D) Treatment of 1,2-dibenzoylhydrazines with phosphorus pentasulfide inpyridine by heating at a temperature of from about 200° C. to about 300°C. for from about 1 to about 3 hours, preferably at 250° C. for about 2hours.

(E) Oxidation of thiobenzoylhydrazones of aromatic aldehydes; or

(F) Reaction of phenyl substituted 1-chloro-1,4-diphenyldiazabutadieneswith potassium ethylxanthate in ethanol at 60° C. for one hour toprovide the phenyl substituted1,4-diphenyl-1-ethylxanthyl-2,3-diazabutadiene which is cyclized to thephenyl substituted 2,5-diphenyl-1,3,4-thiadiazole by heating at atemperature of from about 200° C. to about 260° C. for from about 8 toabout 30 hours, preferably at 240° C. for 20 hours. Reaction of phenylsubstituted 1-chloro-1,4-diphenyldiazabutadienes with sodiumhydrosulfide in refluxing ethanol for 0.5 hour provides the phenylsubstituted 2,5-diphenyl-1,3,4-thiadiazole. Reaction of phenylsubstituted 1-chloro-1,4-diphenyldiazabutadienes with thiourea inrefluxing dry ethanol for four hours provides the phenyl substituted2,5-diphenyl-1,3,4-thiadiazole.

A specific synthesis of 2,5-(4-hydroxyphenyl)thiadiazole and2,5-(2-hydroxyphenyl)thiadiazole via the reaction of4-hydroxybenzaldehyde or 2-hydroxybenzaldehyde, respectively, withsulfur and hydrazine monohydrate using the aforementioned Willergrodtconditions is taught by Mazzone, et al, Journal of HeterocyclicChemistry, volume 20, pages 1399-1401 (1983).

Likewise, a specific synthesis of 2,5-(4-nitrophenyl)thiadiazole fromthe corresponding 4-nitrobenzaldehyde precursor using the aforementionedWillergrodt conditions is taught by the aforementioned Mazzone, et alreference. The nitro groups of said thiadiazole can be reduced usingconventional methods well established in the art to the correspondingamino groups to provide 2,5-(4-aminophenyl)thiadiazole. A specificsynthesis of 2,5-(3-methylphenyl)thiadiazole from the corresponding3-methylbenzaldehyde precursor using the aforementioned Willergrodtconditions is taught by the aforementioned Mazzone, et al reference. Themethyl groups can be oxidized with potassium permanganate in aqueouspyridine by heating at a temperature of from about 40° C. to about 100°C. for from about 1 to about 24 hours, preferably at 60° C. to 80° C.for from about 2 to about 8 hours using the method taught by Javaid andSmith, Journal of Chemical Research (S), pages 118-119 (1984) to provide2,5-(3-carboxyphenyl)thiadiazole.

The 2,5-diaryl substituted-1,3,4-oxadiazoles are prepared via any of thefollowing reactions:

(A) Treatment of substituted 1,2-dibenzoylhydrazines with phosphorusoxychloride, typically at reflux for from about 3 hours to about 24hours. Solvents such as excess phosphorus oxychloride,N-methyl-2-pyrrolidone and N-cyclohexyl-2-pyrrolidone are useful forconducting this reaction; or

(B) Treatment of substituted 1,2-dibenzoylhydrazines with dehydratingagents such as thionyl chloride, polyphosphoric acid (by heating at atemperature of from about 100° C. to about 205° C. for from about 10minutes to about 5 hours, preferably at 185° C. to 205° C. for 10minutes) phosphorous pentoxide (by heating at a temperature of fromabout 200° C. to about 300° C. for from about 1 to about 3 hours,preferably at 250° C. for about 2 hours), acetic anhydride, sulfurtrioxide, or methanesulfonic acid and phosphorous pentoxide mixture; or

(C) Cyclization of disilyldiacyldiarylhydrazines in the presence ofbasic, acidic, neutral (transition metals on inert supports) or freeradical initiators as catalysts, using the methods of Rigo, et al,Synthetic Communications, volume 19, pages 2321-2335 (1989). As aspecific example of these methods, addition of abistrimethylsilyldiacylhydrazine to trifluoromethane sulfonic acidcatalyst (11 percent) under a nitrogen atmosphere, followed by heatingat 75° C. for 3 hours then evaporation to remove hexamethyldisiloxaneproduced a quantitative yield of cyclized product.

A specific synthesis of 2,5-[4-(3-aminophenoxy)]-1,3,4-oxadiazole viathe reaction of 2,5-(4-fluorophenyl)thiadiazole with 3-aminophenol,using N-methyl-2-pyrrolidone and N-cyclohexyl-2-pyrrolidone solvents inthe presence of potassium carbonate is taught by Hedrick, PolymerPreprints, volume 33, number 1, pages 1016-1017 (April, 1992). Thereaction is initially conducted at 150° C. with removal of water fromthe phenoxide formed, followed by displacement reaction at 185° C. fortwenty hours. A specific synthesis of 2,5-(carboxylphenyl)oxadiazolesvia oxidization of the methyl groups of the 2,5-(methylphenyl)oxadiazoleprecursor with potassium permanganate in aqueous pyridine by heating ata temperature of from about 40° C. to about 100° C. for from about 1 toabout 24 hours, preferably at 60° C. to 80° C. for from about 2 to about8 hours, is taught by Javaid and Smith, Journal of Chemical Research(S), pages 118-119 (1984).

Epoxy Resins Containing Thiadiazole, Oxadiazole or both Thiadiazole andOxadiazole Moieties

Typical of the epoxy resins containing one or more thiadiazole,oxadiazole or both thiadiazole and oxadiazole moieties of the presentinvention are those represented by the following Formula II:

Formula II

    G--Z--Ar--(X.sup.1).sub.n --Z--(X.sup.1).sub.n --(Ar--(X.sup.1).sub.n --Z--(X.sup.1).sub.n).sub.n.sup.1 --Ar--Z--G

wherein each Z is independently a --O--, --S--, --NR--, --N< or --COO--group; G is ##STR4## J is hydrogen or a hydrocarbyl group having fromone to about 4, preferably one, carbon atom(s); each Z is independentlya ##STR5## each Ar is independently a ##STR6## each X¹ is independentlya --O--, --S--, --SO--, --SO₂ --, --CO--, --O--CO--, --CO--O--,--S--CO--, --CO--S--, --NR--CO--, --CO--NR--, --NR--CO--NH--,--NH--CO--NR--, --NH--CO--O-- or --O--CO--NH-- group; each R isindependently hydrogen or a hydrocarbyl group having from one to about10, preferably from one to about 4, carbon atoms; each Y isindependently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom one to about 10, preferably from one to about 4, carbon atoms, ahalogen atom, preferably chlorine, bromine or fluorine, a nitro group, anitrile group, a --CO--R group or a --CO--OR group; A is a divalenthydrocarbyl group having from one to about 10, preferably from one toabout 4, carbon atoms and can also contain one or more heteroatomsselected from N, O, and S; each n independently has a value of zero orone and n¹ has a value of zero to about 10.

The term hydrocarbyl as employed herein means any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic or aryl substitutedcycloaliphatic or aliphatic substituted or cycloaliphatic substitutedaromatic groups. The aliphatic or cycloaliphatic groups can be saturatedor unsaturated. Likewise, the term hydrocarbyloxy means a hydrocarbylgroup having an oxygen linkage between it and the carbon atom to whichit is attached.

Certain of the epoxy resins are mesogenic, for example, thoserepresented by the aforementioned Formula II wherein at least about 80percent of the molecules are para substituted by the N and Q--Z-- groupsand the X¹ groups which are present when n has a value of one, X¹ whenpresent is selected from the group consisting of --O--CO--, --CO--O--,--S--CO--, --CO--S--, --NR--CO--, --CO--NR--, and each Ar isindependently selected from the group consisting of ##STR7## whereineach Y is independently hydrogen or a methyl group, with the provisothat no more than one Y group per aromatic ring is a methyl group.

The term "mesogenic" or "mesogen" as is used herein designates compoundscontaining one or more rigid rodlike structural units which have beenfound to favor the formation of liquid crystal phases in the case of lowmolar mass substances. Thus the mesogen or mesogenic moiety is thatstructure responsible for molecular ordering. The term mesogenic isfurther defined by R. A. Weiss (ed.) and C.K. Ober (ed.) inLiquid-Crystalline Polymers, ACS Symposium Series 435 (1989) on page 2:"The rigid unit responsible for the liquid crystalline behavior isreferred to as the mesogen," and "Liquid crystalline order is aconsequence solely of molecular shape anisotropy, such as found in rigidrodshaped molecules . . . ". Further definition of the term mesogenicmay be found in Polymeric Liquid Crystals, Alexandre Blumstein (ed.),(1983) on pages 2-3 and in Polymeric Liquid Crystals, A. Ciferri, W. R.Krigbaum and Robert B. Meyer (eds.) (1982) on pages 5-9, both of whichare incorporated herein by reference.

Representative of the epoxy resins containing one or more thiadiazole,oxadiazole or both thiadiazole and oxadiazole moieties include, forexample, the diglycidyl ethers of: 2,5-(4-hydroxyphenyl)thiadiazole,2,5-(4-hydroxyphenyl)oxadiazole, 2,5-(3-hydroxyphenyl)thiadiazole,2,5-(3-hydroxyphenyl)oxadiazole, 2,5-(2-hydroxyphenyl)thiadiazole,2,5-(2-hydroxyphenyl)oxadiazole,2,5-(3-cyano-4-hydroxyphenyl)thiadiazole,2,5-(3-nitro-4-hydroxyphenyl)-thiadiazole,2,5-(3-bromo-4-hydroxyphenyl)thiadiazole,2,5-(3-methyl-4-hydroxyphenyl)thiadiazole, ##STR8## the diglycidylesters of: 2,5-(4-carboxyphenyl)thiadiazole and2,5-(4-carboxyphenyl)oxadiazole; the diglycidyl thioethers of:2,5-(4-mercaptophenyl)thiadiazole and 2,5-(4-mercaptophenyl)oxadiazole;the diglycidyl amines of: 2,5-(4-aminophenyl)thiadiazole,2,5-(4-aminophenyl)oxadiazole, 2,5-(4-N-methylaminophenyl)thiadiazoleand 2,5-(4-N-methylaminophenyl)oxadiazole. Especially preferred epoxyresin compositions are the diglycidyl ethers of:2,5-(4-hydroxyphenyl)thiadiazole and 2,5-(4-hydroxyphenyl)oxadiazolebecause of their mesogenic character.

Epoxidation of the diphenol, dicarboxylic acid, dithiophenol and diaminocompounds used to prepare the epoxy resins containing one or morethiadiazole, oxadiazole or both thiadiazole and oxadiazole moieties ofthe present invention can be performed by the known methods described inHandbook of Epoxy Resins by Lee and Neville, McGraw-Hill, 1967; JapanKokai Tokkyo Koho JP 62 86,484 (87 96,484); EP 88-008358/92 and Journalof Applied Polymer Science, volume 23, pages 1355-1372 (1972) all ofwhich are incorporated herein by reference. This usually includesreacting the respective diphenol (dicarboxylic acid, dithiophenol ordiamino compound) with an excess of an epihalohydrin such as, forexample, epichlorohydrin, methyl epichlorohydrin or epibromohydrin, at atemperature of from about 0° C. to about 100° C., preferably from about20° C. to about 65° C. followed by dehydrohalogenation with abasic-acting material such as, for example, an alkali metal hydroxide,typically sodium hydroxide, at a temperature of from about 0° C. toabout 100° C., preferably from about 20° C. to about 65° C. and finallyrecovering the resulting glycidyl ether (ester, thioether or amine)product. A prefered method for the production of the epoxy resins of thepresent invention is the use of an anhydrous epoxidation technique. Thistechnique employs azeotropic removal of water/epichlorohydrin concurrentwith the controlled addition of the aqueous sodium hydroxide to areaction mixture consisting of epichlorohydrin, a diphenol (dicarboxylicacid, dithiophenol, diamine), a phase transfer catalyst such as, forexample, benzyltrimethylammonium chloride or tetra-n-butylammoniumbromide, and, optionally, solvent(s). It is advantageous to conduct suchanhydrous epoxidation reactions under a vacuum to facilitate theazeotropic removal of water. The azeotropic removal of water is usuallyconducted at temperatures of from about 20° C. to about 100° C.,preferably from about 30° C. to about 65° C. It is also operable andadvantageous to utilize sodium hydroxide free of water as the alkalimetal hydroxide reactant. In order to control reaction exotherm, thesolid sodium hydroxide is typically added in aliquots as a powder to theepoxidation reaction mixture. A typical anhydrous epoxidation techniqueis described by Wang, et al. in U.S. Pat. No. 4,499,255 which isincorporated herein by reference in its entirety.

Another specific anhydrous epoxidation technique involves catalyticcoupling of the diphenol (dicarboxylic acid, dithiophenol, diamine)compound with an epihalohydrin, typically using as a catalyst one ormore of the quaternary ammonium halides. The resultant solution ofhalohydrin in excess epihalohydrin is then treated with finelypulverized potassium carbonate to effect the dehydrohalogenation to theepoxy resin.

Advanced Epoxy Resins Containing Thiadiazole, Oxadiazole or bothThiadiazole and Oxadiazole Moieties

Advancement reaction of the epoxy resins containing one or morethiadiazole, oxadiazole or both thiadiazole and oxadiazole moieties withone or more compounds having an average of more than one active hydrogenatom per molecule can be performed by the known methods described in theaforementioned Handbook of Epoxy Resins. This usually includes combiningthe compound(s) having an average of more than one hydrogen atomreactive with an epoxide group per molecule and the epoxy resin(s) withthe application of heat and mixing to effect the advancement reaction. Acatalyst is frequently added to facilitate the advancement reaction.

The epoxy resin(s) and the compound(s) having an average of more thanone hydrogen atom reactive with an epoxide group per molecule arereacted in amounts which provide suitably from about 0.001:1 to about0.94:1, more suitably from about 0.05:1 to about 0.8:1, most suitablyfrom about 0.1:1 to about 0.5:1 equivalents of active hydogen atoms perequivalent of epoxide group.

Suitable compounds having an average of more than one hydrogen atomreactive with an epoxide group per molecule which can be employed toprepare the advanced epoxy resin compositions of the present inventioninclude, for example, diphenols, dicarboxylic acids, thiodiphenols,compounds containing one primary amine group, compounds containing oneprimary or secondary amide group and one primary or secondary aminegroup, compounds containing two secondary amine groups, compoundscontaining one primary or secondary amine group and one --SO₂ --NH₂group, compounds containing one phenolic hydroxyl group and onecarboxylic acid group, compounds containing one phenolic hydroxyl groupand one primary or secondary amine group, compounds containing onecarboxylic acid group and one primary or secondary amine group, or anycombination thereof and the like.

Especially preferred as the compound having an average of more than onehydrogen atom reactive with an epoxide group per molecule are thecompounds which contain one or more thiadiazole, oxadiazole or boththiadiazole and oxadiazole moieties represented by Formula I. Additionalcompounds having an average of more than one hydrogen atom reactive withan epoxide group per molecule include diphenols, such as, for example,hydroquinone, resorcinol, 4,4'-isopropylidenediphenol (bisphenol A),4,4'-dihydroxydiphenylmethane, 4,4'-thiodiphenol, 4,4'-sulfonyldiphenol,4,4'-dihydroxydiphenyl oxide, 4,4'-dihydroxybenzophenone,1,1-bis(4-hydroxyphenyl)-1-phenylethane,3,3',3,5'-tetrachloro-4,4'-isopropylidenediphenol,3,3',3,5'-tetrabromo-4,4'-isopropylidenediphenol,3,3'-dimethoxy-4,4'-isopropylidenediphenol, 4,4'-dihydroxybiphenyl,4,4'-dihydroxy-alpha-methylstilbene, 4,4'-dihydroxybenzanilide,bis(4-hydroxyphenyl)terephthalate,N,N'-bis(4-hydroxyphenyl)terephthalamide,bis(4'-hydroxybiphenyl)terephthalate, 4,4'-dihydroxyphenylbenzoate,bis(4'-hydroxyphenyl)-1,4-benzenediimine; dicarboxylic acids, such as,for example, terephthalic acid, isophthalic acid,4,4'-benzanilidedicarboxylic acid, 4,4'-phenylbenzoatedicarboxylic acid,4,4'-stilbenedicarboxylic acid, adipic acid; thiodiphenols, such as, forexample, 4,4'-dithiodiphenylmethane, 4,4'-isopropylidenedithiophenol,4,4'-dithio-alpha-methylstilbene; compounds containing one primary aminegroup, such as, for example, aniline, 4-methoxyaniline, 4-aminobiphenyl,4-amino-N-methylbenzanilide, 4-amino-1-phenylbenzoate,phenyl-4-aminobenzoate, biphenyl-4-aminobenzoate,1-phenyl-4'-aminophenylterephthalate; compounds containing one primaryor secondary amide group and one primary or secondary amine group, suchas, for example 4-aminobenzamide, 4-N-methylaminobenzamide,4-amino-N-methylbenzamide, 4-N-methylamino-N-methylbenzamide; compoundscontaining two secondary amine groups, such as, for example,4,4'-(N,N'-methylamino)diphenylmethane, 4,4'-(N,N'-methylamino)biphenyl;compounds containing one primary or secondary amine group and one --SO₂--NH₂ group, such as, for example, sulfanilamide,4-amino-4'-sulfonamidobiphenyl, 4-N-methylamino-4'-sulfonamidobiphenyl;compounds containing one phenolic hydroxyl group and one carboxylic acidgroup, such as, for example, 4-hydroxybenzoic acid,4-hydroxy-4-carboxybiphenyl; compounds containing one phenolic hydroxylgroup and one primary or secondary amine group, such as, for example,4-aminophenol, 4-N-methylaminophenol, 4-amino-4-hydroxybiphenyl andcompounds containing one carboxylic acid group and one primary orsecondary amine group, such as, for example, 4-aminobenzoic acid,4-N-methylaminobenzoic acid, 4-amino-4-carboxybiphenyl.

The advancement reaction reaction can be conducted in the presence of asuitable advancement catalyst such as, for example, phosphines,quaternary ammonium compounds, phosphonium compounds, tertiary amines,and the like. Particularly suitable catalysts include, for example,ethyltriphenylphosphonium chloride, ethyltriphenylphosphonium bromide,ethyltriphenylphosphonium iodide, ethyltriphenylphosphonium diacetate(ethyltriphenylphosphonium acetate-acetic acid complex),ethyltriphenylphosphonium phosphate, tetrabutylphosphonium chloride,tetrabutylphosphonium bromide, tetrabutylphosphonium iodide,tetrabutylphosphonium diacetate (tetrabutylphosphonium acetate-aceticacid complex), butyltriphenylphosphonium tetrabromobisphenate,butyltriphenylphosphonium bisphenate, butyltriphenylphosphoniumbicarbonate, benzyltrimethylammonium chloride, tetramethylammoniumhydroxide, tetra-n-butylammonium chloride, tetra-n-butylammoniumbromide, triethylamine, tripropylamine, tributylamine,2-methylimidazole, benzyldimethylamine, mixtures thereof and the like.Many of these catalysts are described in U.S. Pat. Nos. 3,306,872;3,341,580; 3,379,684; 3,477,990; 3,547,881; 3,637,590; 3,843,605;3,948,855; 3,956,237; 4,048,141; 4,093,650; 4,131,633; 4,132,706;4,171,420; 4,177,216 and 4,366,295, all of which are incorporated hereinby reference.

The amount of advancement catalyst depends upon the particular reactantsand catalyst employed, as well as the advancement reaction conditions tobe used, however, it is usually employed in quantities of from about0.03 to about 3, preferably from about 0.03 to about 1.5, mostpreferably from about 0.05 to 1.5 percent by weight based upon theweight of the epoxy-containing compound.

The advancement reaction can be conducted at atmospheric,superatmospheric or subatmospheric pressures at temperatures of fromabout 20° C. to about 260° C., preferably from about 80° C. to about240° C., more preferably from about 100° C. to about 200° C. The timerequired to complete the advancement reaction depends upon thetemperature employed. Higher temperatures require shorter periods oftime whereas lower temperatures require longer periods of time.Generally, however, times of from about 5 minutes to about 24 hours,preferably from about 30 minutes to about 8 hours, more preferably fromabout 30 minutes to about 3 hours are suitable.

If desired, the advancement reaction can be conducted in the presence ofone or more solvents. Such solvents include, for example, glycol ethers,aliphatic and aromatic hydrocarbons, aliphatic ethers, cyclic ethers,ketones, esters, amides, combinations thereof and the like. Particularlysuitable solvents include, for example, toluene, xylene, methylethylketone, methylisobutyl ketone, diethylene glycol methyl ether,dipropylene glycol methyl ether, dimethylformamide, dimethylsulfoxide,N-methylpyrrolidinone, tetrahydrofuran, dioxane, propylene glycol methylether, combinations thereof and the like. The solvents can be employedin amounts from about zero to about 95%, preferably from about 20% toabout 60%, more preferably from about 30% to about 50% by weight of thereaction mixture.

The advancement of the epoxy resins containing one or more thiadiazole,oxadiazole or both thiadiazole and oxadiazole moieties with one or morecompounds having an average of more than one active hydrogen atom permolecule is employed to chain extend and/or branch the resin. This chainextension and/or branching is required for some of the mesogencontaining resin compositions in order to obtain liquid crystalcharacter. The advancement of the of the epoxy resins containing one ormore thiadiazole, oxadiazole or both thiadiazole and oxadiazole moietiescan also be used to modify the temperature range in which a particularmesogen-containing resin is liquid crystalline and to control the degreeof crosslinking during the final curing. An especially preferredmesogenic advanced epoxy resin composition of the present inventionresults from the advancement reaction of one of the aforementionedmesogenic epoxy resins containing one or more thiadiazole, oxadiazole orboth thiadiazole and oxadiazole moieties with one or more mesogeniccompounds represented by the aforementioned Formula I wherein at leastabout 80 percent of the molecules are para substituted by the N and Xgroups and the X¹ groups which are present when n has a value of one, X¹when present is --O--CO--, --CO--O--, --S--CO--, --CO--S--, --NR--CO--,or --CO--NR--, each Ar is independently a ##STR9## wherein each Y isindependently a hydrogen atom or a methyl group with the proviso that nomore than one Y group per aromatic ring is a methyl group, and X is--OH, --NHR or --COOH, with the proviso that when X is --NHR, each R isindependently a hydrocarbyl group having from one to about 10,preferably one to about 4, carbon atoms.

Phenoxy Resins Containing Thiadiazole, Oxadiazole or both Thiadiazoleand Oxadiazole Moieties

When the epoxy resin containing one or more thiadiazole, oxadiazole orboth thiadiazole and oxadiazole moieties and the compound having anaverage of more than one active hydrogen atom per molecule are reactedin advancement reaction using amounts which provide suitably from about0.95:1 to about 1.05:1 equivalents of active hydogen atoms perequivalent of epoxide group, a relatively high molecular weightthermoplastic resinous product (sometimes referred to as a phenoxyresin) is produced. If desired, the reaction can be conducted in thepresence of a suitable catalyst such as, for example, those catalystsdescribed herein for use in the advancement reaction. Thesethermoplastic resin compositions contain little, if any, curableresidual epoxide functionality and may even contain an active hydrogenfunctionality, depending upon which component is employed in excess, theepoxy resin, or the active hydrogen containing compound. When thecompound having an average of more than one active hydrogen atom permolecule used in the advancement reaction is a diphenol, the resultantresinous product is a phenoxy resin. These phenoxy resins may thus beprocessed using the typical processing methods employed withconventional thermoplastic resins, such as, for example, injectionmolding or extrusion. Thermosetting may, however, be induced, forexample, via reaction of all or a part of the backbone secondaryaliphatic hydroxyl groups produced in the aforesaid advancementreaction, with a curing agent therefore. One class of suitable curingagents includes, for example, the di or polyisocyanates, as well as theblocked di or polyisocyanates which can be induced to react with thesecondary hydroxyl groups providing urethane crosslinks between theresin chains. An example of a diisocyanate especially useful herein is4,4'-diisocyanatodiphenyl methane.

According to the teachings found in Encyclopedia of Polymer Science andEngineering, volume 6, page 331, published by John Wiley and Sons, NewYork, N.Y. (1986), which is incorporated herein by reference, aside fromthe aforementioned advancement method, a phenoxy resin may also beprepared by reaction of a 1:1 mole ratio of high purity bisphenol A andepichlorohydrin. It is therefore operable to prepare the phenoxy resinsof the present invention via reaction of one or more diphenols with oneor more epihalohydrins. A typical material would thus be the phenoxyresin produced from the reaction of epichlorohydrin and2,5-(4-hydroxyphenyl)thiadiazole using the aforementioned stoichiometricratio. The reaction of the epihalohydrin and the bisphenol is usuallyconducted at a temperature of from about 0° C. to about 100° C.,preferably from about 20° C. to about 80° C., more preferably from about20° C. to about 65° C. for a time sufficient to complete the reaction,usually from about one to about 12, preferably from about one to about5, more preferably from about one to about 3 hours.

An especially preferred mesogenic phenoxy resin composition of thepresent invention results from the advancement reaction of one of theaforementioned mesogenic epoxy resins containing one or morethiadiazole, oxadiazole or both thiadiazole and oxadiazole moieties withone or more mesogenic compounds represented by the aforementionedFormula I wherein at least about 80 percent of the molecules are parasubstituted by the N and X groups and the X¹ groups which are presentwhen n has a value of one, X¹ when present is a --O--CO--, --CO--O--,--S--CO--, --CO--S--, --NR--CO--, or --CO--NR group, each Ar isindependently a ##STR10## wherein each Y is independently a hydrogenatom or a methyl group with the proviso that no more than one Y groupper aromatic ring is a methyl group; X is --OH, --SH, --NHR,or --COOH,with the proviso that when X is --NHR, each R is independently ahydrocarbyl group having from one to about 10, preferably one to about4, carbon atoms.

Curing Agents and Curing Catalysts

The epoxy resins containing one or more thiadiazole, oxadiazole or boththiadiazole and oxadiazole moieties of the present invention can becured with with any suitable curing agent or catalyst for curing epoxyresins, such as, for example, aliphatic, cycloaliphatic,polycycloaliphatic or aromatic primary monoamines; aliphatic,cycloaliphatic, polycycloaliphatic or aromatic primary and secondarypolyamines; carboxylic acids and anhydrides thereof; aromatic hydroxylcontaining compounds; imidazoles; guanidines; urea-aldehyde resins;melamine-aldehyde resins; alkoxylated urea-aldehyde resins; alkoxylatedmelamine-aldehyde resins; combinations thereof and the like.Particularly suitable curing agents include, for example,methylenedianiline, dicyandiamide, ethylene diamine, diethylenetriamine,triethylenetetramine, tetraethylenepentamine, urea-formaldehyde resins,melamine-formaldehyde resins, methylolated urea-formaldehyde resins,methylolated melamine-formaldehyde resins, phenol-formaldehyde novolacresins, cresol-formaldehyde novolac resins, sulfanilamide,diaminodiphenylsulfone, diethyltoluenediamine, t-butyltoluenediamine,bis-4-aminocyclohexylamine, isophoronediamine, diaminocyclohexane,hexamethylenediamine, piperazine, aminoethylpiperazine,2,5-dimethyl-2,5-hexanediamine, 1.12-dodecanediamine,tris-3-aminopropylamine, combinations thereof and the like. Particularlysuitable curing catalysts include boron trifluoride, boron trifluorideetherate, aluminum chloride, ferric chloride, zinc chloride, silicontetrachloride, stannic chloride, titanium tetrachloride, antimonytrichloride, boron trifluoride monoethanolamine complex, borontrifluoride triethanolamine complex, boron trifluoride piperidinecomplex, pyridine-borane complex, diethanolamine borate, zincfluoroborate, or any combination thereof and the like.

Especially preferred: as curing agents for the mesogenic epoxy resincomposition and mesogenic advanced epoxy resin compositions of thepresent invention are one or more mesogenic compounds represented by theaforementioned Formula I wherein at least about 80 percent of themolecules are para substituted by the N and X groups and the X¹ groupswhich are present when n has a value of one, X¹ when present is a--O--CO--, --CO--O--, --S--CO--, --CO--S--, --NR--CO--, or --CO--NRgroup; each Ar is independently ##STR11## wherein each Y isindependently a --H or --CH₃ group with the proviso that no more thanone Y group per aromatic ring is --CH₃ and X and R are as hereinbeforedefined.

The curing agents are generally employed in amounts which willeffectively cure the epoxy resin, however, these amounts will dependupon the particular epoxy resin employed:and curing agent employed.Generally suitable amounts include, for example, 0.80:1 to about 1.20:1equivalents of curing agent per equivalent of epoxy resin.

The curing catalysts are employed in amounts which will effectively curethe composition, however, these amounts will depend upon the particularepoxy resin employed:and curing agent employed. Generally suitableamounts include, for example, 0.001 to about 2 percent by weight of thetotal epoxy resin used. It is frequently of benefit to employ one ormore of the curing catalysts in conjunction with one or more curingagents in the curing of the epoxy resins of the present invention. Thisis generally done to accelerate or otherwise modify the curing behaviorobtained when a curing agent or a curing catalyst are used singly.

The curing of the curable compositions of the present invention can beconducted at atmospheric, superatmospheric or subatmospheric pressuresat temperatures of from about 0° C. to about 300° C., preferably fromabout 50° C. to about 240° C., more preferably from about 100° C. toabout 200° C. The time required to complete the advancement reactiondepends upon the temperature employed. Higher temperatures requireshorter periods of time whereas lower temperatures require longerperiods of time. Generally, however, times of from about one minute toabout 48 hours, preferably from about 15 minutes to about 8 hours, morepreferably from about 30 minutes to about 3 hours are suitable.

For the curable blends of epoxy resins and/or advanced epoxy resins ofthe present invention with one or more curing agents, when mesogenicmoieties are present in one or more components of said blends, it isfrequently of value to B-stage the curable blend in order to chainextend the resin. This chain extension is required for some mesogencontaining epoxy resin compositions in order to achieve liquid crystalcharacter. B-staging can also be employed to increase the temperaturerange at which a particular resin composition is liquid crystalline andto control the degree of crosslinking during the final curing stage.

For the curable blends of epoxy resins and/or advanced epoxy resins ofthe present invention with one or more curing agents, when mesogenicmoieties are present in one or more components of said blends, beforeand/or during processing and/or curing into a part, electric or magneticfields, drawing and/or shear stresses can be applied for the purpose oforienting the liquid crystal moieties contained or developed thereinwhich in effect improves the mechanical properties. As specific examplesof these methods, Finkelmann, et al, Macromol. Chem., volume 180, pages803-806 (March, 1979) induced orientation in thermotropic methacrylatecopolymers containing mesogenic side chain groups decoupled from themain chain via flexible spacers in an electric field. Orientation ofmesogenic side chain groups decoupled from the polymer main chain viaflexible spacers in a magnetic field has been demonstrated by Roth andKruecke, Macromol. Chem., volume 187, pages 2655-2662 (November, 1986).Magnetic field induced orientation of mesogenic main chain containingpolymers has been demonstrated by Moore, et al, ACS Polymeric MaterialsSciences and Engineering, volume 52, pages 84-86 (April-May, 1985).Magnetic and electric field orientation of low molecular weightmesogenic compounds is discussed by W. R. Krigbaum in Polymer LiquidCrystals, pages 275-309 (1982) published by Academic Press, Inc. All ofthe above are incorporated herein by reference in their entirety.

In addition to orientation by electric or magnetic fields, polymericmesophases can be oriented by shear forces which are induced by drawingand/or flow through dies, orefices and mold gates. A general discussionfor orientation of thermotropic liquid crystal polymers by this methodis given by S. K. Garg and S. Kenig in High Modulus Polymers, pages71-103 (1988) published by Marcel Dekker, Inc. For the mesomorphicsystems based on the epoxy and phenoxy resin compositions, this shearorientation can be produced by processing methods such as injectionmolding, extrusion, pultrusion, filament winding, filming andprepreging.

Other Epoxy Resins

The epoxy resins containing one or more thiadiazole, oxadiazole or boththiadiazole and oxadiazole moieties can also be combined with one ormore epoxy resins free of thiadiazole and/or oxadiazole moieties.Generally, suitable amounts of the epoxy resins containing one or morethiadiazole, oxadiazole or both thiadiazole and oxadiazole moieties arefrom about 1 to about 99, more suitably from about 10 to about 80, mostsuitably from about 10 to about 50 weight percent based on the totalweight of the combined resins. Curable mixtures may be formed viaaddition of one or more of the aforementioned curing agents and/orcuring catalysts.

Suitable epoxy resins which..can be combined with the epoxy resinscontaining one or more thiadiazole, oxadiazole or both thiadiazole andoxadiazole moieties include any compound containing an average of morethan one vicinal epoxide group per molecule and no thiadiazole and/oroxadiazole moieties. Suitable such epoxy resins include, for example,aromatic di and/or polyepoxides, aliphatic di and/or polyepoxides,cycloaliphatic or polycycloaliphatic di and/or polyepoxides, or anycombination thereof and the like. Particularly suitable epoxy resinsinclude the diglycidyl ethers of (a) compounds containing one or morearomatic rings and two or more aromatic hydroxyl groups per molecule;(b) compounds which are the result of reacting an alkytene oxide ormonoglycidyl ether compound with the compounds of (a); (c) aliphaticdiols which contain ether oxygen atoms or which are free of ether oxygenatoms; (d) cycloaliphatic or polycycloaliphatic compounds containingmore than one hydroxyl group per molecule.

Particularly suitable epoxy resins include, for example, (a) thediglycidyl ethers of: resorcinol, hydroquinone,4,4'-isopropylidenediphenol (bisphenol A), 4,4'-dihydroxydiphenylmethane(bisphenol F), 4,4'-dihydroxybenzophenone,3,3'5,5'-tetrabromo-4,4'-isopropylidenediphenol, 4,4'-thiodiphenol,4,4'-sulfonyldiphenol, 4,4'-dihydroxydiphenyl oxide,1,1-bis(4-hydroxyphenyl)-1-phenylethane,3,3',5,5'-tetrachloro-4,4'-isopropylidenediphenol A,3,3'-dimethoxy-4,4'-isopropylidenediphenol,4,4'-dihydroxy-alpha-methylstilbene, 4,4'-dihydroxybenzanilide,4,4'-dihydroxyazoxybenzene, 4,4'-dihydroxybiphenyl; (b) the triglycidylether of tris(hydroxyphenyl)methane; (c) the polyglycidyl ethers of aphenol or alkyl or halogen substituted phenolaldehyde acid catalyzedcondensation product (novolac resins); the polyglycidyl ether of thecondensation product of a dicyclopentadiene or an oligomer thereof and aphenol or alkyl or halogen substituted phenol; (d) the advancementreaction products of the aforesaid di and polyglycidyl ethers witharomatic di and polyhydroxyl or carboxylic acid containing compoundsincluding, for example hydroquinone, resorcinol, catechol,2,4-dimethylresorcinol 4-chlororesorcinol, tetramethylhydroquinone,4,4'-isopropylidenediphenol (bisphenol A),4,4'-dihydroxydiphenylmethane, 4,4'-thiodiphenol, 4,4'-sulfonyldiphenol,2,2'-sulfonyldiphenol, 4,4'-dihydroxydiphenyl oxide,4,4'-dihydroxybenzophenone, 1,1-bis(4-hydroxyphenyl)-1-phenylethane,4,4'-bis(4(4-hydroxyphenoxy)-phenylsulfone)diphenyl ether,4,4'-dihydroxydiphenyl disulfide,3,3',3,5'-tetrachloro-4,4'-isopropylidenediphenol,3,3',3,5'-tetrabromo-4,4'-isopropylidenediphenol,3,3'-dimethoxy-4,4'-isopropylidenediphenol, 4,4'-dihydroxybiphenyl,4,4'-dihydroxy-alpha-methylstilbene, 4,4'-dihydroxybenzanilide,bis(4-hydroxyphenyl)terephthalate,N,N'-bis(4-hydroxyphenyl)terephthalamide,bis(4'-hydroxybiphenyl)terephthalate, 4,4'-dihydroxyphenylbenzoate,bis(4'-hydroxyphenyl)-1,4-benzenediimine;1,1'-bis(4-hydroxyphenyl)cyclohexane, phloroglucinol, pyrogallol,2,2',5,5'-tetrahydroxydiphenyl sulfone, tris(hydroxyphenyl)methane,dicyclopentadiene diphenol, tricyclopentadiene diphenol, terephthalicacid, isophthalic acid, 4,4'-benzanilidedicarboxylic acid,4,4'-phenylbenzoatedicarboxylic acid, 4,4'-stilbenedicarboxylic acid,adipic acid; and (e) any combination of the aforementioned epoxy resinsand the like.

Other Components

The epoxy resins containing one or more thiadiazole, oxadiazole or boththiadiazole and oxadiazole moieties or such epoxy resins in combinationwith other epoxy resins can be blended with other materials such assolvents or diluents, fillers, pigments, dyes, flow modifiers,thickeners, reinforcing agents, mold release agents, wetting agents,stabilizers, fire retardant agents, surfactants, or any combinationthereof and the like.

These additives are added in functionally equivalent amounts, e.g., thepigments and/or dyes are added in quantities which will provide thecomposition with the desired color; however, they are suitably employedin amounts of from about zero to about 20, more suitably from about 0.5to about 5, most suitably from about 0.5 to about 3 percent by weightbased upon the weight of the total blended compositions.

Solvents or diluents which can be employed herein include, for example,hydrocarbons, ketones, glycol ethers, aliphatic ethers, cyclic ethers,esters, amides, combinations thereof and the like. Particularly suitablesolvents or diluents include, for example, toluene, xylene,methylethylketone, methylisobutylketone, diethylene glycol methyl ether,dipropylene glycol methyl ether, dimethylformamide,N-methylpyrrolidinone, tetrahydrofuran, dioxane, propylene glycol methylether, combinations thereof and the like.

The modifiers such as thickeners, flow modifiers and the like can besuitably employed in amounts of from zero to about 10, more suitablyfrom about 0.5 to about 6, most suitably from about 0.5 to about 4percent by weight based upon the weight of the total composition.

Reinforcing materials which can be employed herein include natural andsynthetic fibers in the form of woven fabric, mats, monofilament,multifilament, unidirectional fibers, rovings, random fibers orfilaments, inorganic fillers or whiskers, hollow spheres, and the like.Suitable reinforcing materials include glass, ceramics, nylon, rayon,cotton, aramid, graphite, polyalkylene terephthalates, polyethylene,polypropylene, polyesters, combinations thereof and the like.

Suitable fillers which can be employed herein include, for example,inorganic oxides, ceramic microspheres, plastic microspheres, glassmicrospheres, inorganic whiskers, calcium carbonate, combinationsthereof and the like.

The fillers can be employed in amounts suitably from about zero to about95, more suitably from about 10 to about 80, most suitably from about 40to about 60 percent by weight based upon the weight of the totalcomposition.

The epoxy resins containing one or more thiazole or oxazole or boththiazole and oxazole moieties of the present invention can be employedin such applications as coating, casting, encapsulation, electronic orstructural laminate or composite, filament winding, molding, and thelike.

The following examples are illustrative of the present invention, butare not to be construed as to limiting its scope in any manner.

EXAMPLE 1 A. Synthesis of 2,5-(4-hydroxyphenyl)thiadiazole

p-Hydroxybenzaldehyde (50.0 grams, 0.409 mole), sulfur (26.27 grams,0.819 mole), and ethylene glycol (250 milliters) are added to a oneliter glass reactor equipped with a condenser venting through a scrubbercharged with aqueous sodium hydroxide solution, stirring, a nitrogeninlet flowing at a rate of one liter per minute, an addition funnel anda thermometer-heating mantle-temperature controller assembly. Hydrazinemonohydrate (65.02 grams, 1.299 mole) and additional ethylene glycol(150 milliliters) are added dropwise to the reactor inducing an exothermto 35° C. After completion of the addition, heating to 100° C. commencesover the next 1.5 hours. After 16 hours at the 100° C. temperature, aslurry of crystals are observed in the reactor and are recovered viafiltration. The recovered crystals are transferred to a 316 stainlesssteel one liter Parr reactor along with additional sulfur (12.5 grams,0.39 mole) and ethylene glycol (400 milliters). The Parr reactor issealed, purged with nitrogen, then stirring and heating to 140° C.commence. Once the reactor has stabilized at the 140° C. temperature,gradual heating to 160° C. commences and this temperature is maintainedfor the next 16 hours. The reactor is cooled to room temperature (24°C.) and the resultant crystalline slurry product is recovered andfiltered. The recovered crystals are added to a two liter beaker alongwith ethanol (1800 milliliters) then boiled with stirring to provide ahazy solution. Filtration of the hot, hazy solution is completed and theresulting clear filtrate is cooled to room temperature. After four hoursat room temperature, the crystals formed in the filtrate are recoveredby filtration then dried under vacuum at 100° C. and 1 mm Hg to aconstant weight of 30.6 grams. A second crop of crystals (0.81 gram) arerecovered by rotary evaporation of the filtrate to a volume of 400milliliters followed by cooling to room temperature, filtration anddrying under vacuum. Fourier transform infrared spectrophotometricanalysis of a potassium bromide pellet of the product reveals thepresence of absorptions at 1609, 1583, 1523, 1443 and 1384 cm⁻¹characteristic of the aromatic, ring and the thiadiazole ring, thehydroxyl group O--H stretching centered at 3336 cm⁻¹ and theout-of-plane C--H bending vibration at 839 cm⁻¹ indicative ofpara-disubstitution. Differential scanning calorimetry of a portion ofthe product (14.8 milligrams) heated at 10° C. per minute under nitrogenflowing at 35 cubic centimeters per minute reveals a sharp melting pointendotherm (128.0 joules per gram) with a minimum at 333.2° C. Protonmagnetic resonance spectroscopy and ¹³ carbon magnetic resonancespectroscopy further substantiated the product structure. High pressureliquid chromatographic analysis using an ultraviolet absorbance detectorreveals a single peak comprising 85.7 area % (molar absorptivity notdetermined) of the product, with the balance of the area contained in apair of minor coproduct peaks.

B. Epoxidation of 2,5-(4-hydroxyphenyl)thiadiazole

2,5-(4-Hydroxyphenyl)thiadiazole (13.51 grams, 0.10 hydroxyl equivalent)from A above, epichlorohydrin (462.7 grams, 5.0 moles) andtetrabutylammonium bromide (0.135 gram, 1.00% wt. of the diphenolreactant used) are added to a one liter glass round bottom reactor andheated to 75° C. with magnetically driven stirring under a nitrogenatmosphere flowing at a rate of one liter per minute. The bright yellowcolored reactant slurry becomes a clear solution after 501 minutes atthe 75° C. reaction temperature. After 741 minutes at 75° C., highpressure liquid chromatographic analysis of a portion of the light ambercolored solution demonstrates that complete conversion of the diphenolhas occurred. At this time, a water separator is interspersed betweenthe reactor and the chilled (-2.5° C.) glycol condenser and an additionfunnel containing sodium hydroxide (4.5 grams, 0.1125 mole) dissolved indeionized water (5.5 grams, 55% wt. of the solution) and a vacuum lineare added to the reactor. The nitrogen purge is shut off simultaneouswith initiation of the vacuum. The vacuum and reaction temperature areequilibrated at 69 mm Hg and 50° C., respectively and such that avigorous reflux is maintained with continuous return of dryepichlorohydrin from the water separator to the reactor. Afterequilibration, dropwise addition of the aqueous sodium hydroxidecommences. After 50 minutes, addition of the aqueous sodium hydroxide iscomplete. After an additional 2.5 hours at the 69 mm Hg vacuum and 50°C. reaction temperature, heating ceases, vacuum is released and theproduct slurry recovered. The recovered slurry is filtered through a bedof diatomaceous earth while still hot and the resultant light ambercolored solution rotary evaporated under a vacuum with heating to 90° C.After removal of about 50% of the epichlorohydrin volume, the productbecame a crystalline slurry. Rotary evaporation is continued until about75% of the epichlorohydrin volume is removed. The resultant slurry isallowed to cool to room temperature (23° C.), then filtered after fourhours at room temperature. After filtration the crystalline product isextracted with acetone (100 milliliters) then recovered via filtration.This extraction--filtration sequence is repeated two more times followedby drying in a vacuum oven at 80° C. and 1 mm Hg to provide a constantweight of 13.70 grams of pale tan colored crystalline product. Titrationof a portion of the product reveals an epoxide equivalent weight of205.2 (corrected for titrated contribution of the thiadiazole ring).Fourier transform infrared spectrophotometric analysis of a potassiumbromide pellet of the product reveals the presence of absorptions at1603, 1576, 1516, 1443 and 1410 cm⁻¹ characteristic of the aromatic ringand the thiadiazole ring, disappearance of the hydroxyl group O--Hstretching centered at 3336 cm-1, out-of-plane C--H bending vibration at832 cm⁻¹ indicative of para-disubstitution and epoxide --C--O--stretching absorbance at 866 and 912 cm⁻¹. Differential scanningcalorimetry scanning calorimetry of a portion of the product (13.0milligrams) heated from 30° to 300° C. at 10° C. per minute undernitrogen flowing at 35 cubic centimeters per minute reveals a sharpmelting point endotherm (84.8 joules per gram) with a minimum at 182.4°C. followed by an exotherm (534.8 joules per gram) with a maximum at221.5° C. High pressure liquid chromatographic analysis using anultraviolet absorbance detector reveals a single peak comprising 95.0area % (molar absorptivity not determined) of the product, with thebalance of the area contained in a pair of minor coproduct peaks.

C. Characterization of the Diglycidyl Ether of2,5-(4-hydroxyphenyl)thiadiazole for Liquid Crystallinity

Analysis of a portion of the diglycidyl ether of2,5-(4-hydroxyphenyl)thiadiazole from B above via crosspolarized lightmicroscopy is completed using a microscope equipped with a programmablehot stage with heating from 30° to 220° C. using a heating rate of 10°C. per minute. The results are reported in Table I.

                  TABLE I                                                         ______________________________________                                        OBSERVED                                                                      TRANSITION                                                                    TEMPERATURE (°C.)                                                                    COMMENTS                                                        ______________________________________                                         30           Birefringent, crystalline solid.                                172           First fluidity noted.                                           184           Liquid crystal phase forms with                                               aggregated solid particles present.                             202           Liquid crystal phase clears and solid                                         particles dissolve as coverslip is moved                                      to mix the sample.                                              205           Viscosity increases.                                            220           Thermosets to a non-birefringent solid.                                       Low level of birefringence noted when                                         cooled to 30° C.                                         ______________________________________                                    

The diglycidyl ether is an enantiotropic liquid crystal. Analysis of asecond portion of the diglycidyl ether of2,5-(4-hydroxyphenyl)thiadiazole from B above via crosspolarized lightmicroscopy is completed using a microscope equipped with a programmablehot stage preheated to 184° C. The results are reported in Table II.

                  TABLE II                                                        ______________________________________                                        TIME                                                                          at 184° C. (min.)                                                                 COMMENTS                                                           ______________________________________                                         1        Liquid crystal phase forms with aggregated                                    solid particles present.                                             2        Solid particles dissolve as coverslip is moved to                             mix the sample, opalescent, liquid crystalline.                     10        Solid particles have cleared, opalescent, liquid                              crystalline.                                                        12        Viscosity increases, non-opalescent, non-                                     birefringent.                                                       15        Solidifies, begin cooling, highly birefringent,                               partially opaque solid with a microdomain                                     appearance at 30° C.                                         ______________________________________                                    

EXAMPLE 2 Preparation of a Blend of the Diglycidyl Ether of2,5-(4-Hydroxyphenyl)thiadiazole and 2,5-(4-Hydroxyphenyl)thiadiazoleand Copolymerization

A portion (0.4575 gram, 0.00223 epoxide equivalent) of the diglycidylether of 2,5-(4-hydroxyphenyl)thiadiazole from Example 1-B and a portion(0.3013 gram, 0.02233 hydroxyl equivalent) of2,5-(4-hydroxyphenyl)thiadiazole from Example 1-A are added to a ceramicmortar and ground to a homogeneous powder. Differential scanningcalorimetry analysis of a portion (11.7 milligrams) of the powder blendheated at 10° C. per minute under nitrogen flowing at 35 cubiccentimeters per minute revealed an exotherm (295.8 joules per gram) witha maximum at 175.5° C. Analysis of a portion of the powder blend viacrosspolarized light microscopy is completed using a microscope equippedwith a programmable hot stage with heating from 30° to 225° C. using aheating rate of 10° C. per minute. The results are reported in TableIII.

                  TABLE III                                                       ______________________________________                                        OBSERVED                                                                      TRANSITION                                                                    TEMPERATURE (°C.)                                                                    COMMENTS                                                        ______________________________________                                         0            Birefringent, crystalline solid.                                167           First fluidity noted.                                           179           Powder has fused, highly birefringent                                         liquid crystal phase forms.                                     225           Highly birefringent brown colored                                             solid, begin cooling, highly birefringent                                     opaque solid with crystalline                                                 appearance at 30° C.                                     ______________________________________                                    

EXAMPLE 3 Analysis of Copolymerized Blend of Diclycidyl Ether of2,5-(4-Hydroxyphenyl)thiadiazole and 2,5-(4-Hydroxyphenyl)thiadiazolefor Glass Transition Temperature

A portion (12.55 milligrams) gram of the diglycidyl ether of2,5-(4-hydroxyphenyl)thiadiazole and 2,5-(4-hydroxyphenyl)thiadiazoleblend from Example 2 are cured in a differential scanning calorimeter byheating at 10° C. per minute under a stream of nitrogen flowing at 35cubic centimeters per minute to 170° C., followed by holding at thistemperature for 20 minutes, 10° C. per minute to 190° C., followed byholding at this temperature for 10 minutes, then 10° C. per minute to210° C., followed by holding at this temperature for 10 minutes. Aftergradual cooling to 30° C., a second scan is completed by heating from30° to 300° C. at 10° C. per minute under nitrogen flowing at 35 cubiccentimeters per minute. No events were detected up to a sharp exothermicrise with an onset at 245.4° C. Curing of a second sample (11.20milligrams) of the blend is completed using the aforementionedtime-temperature profile with the addition of heating at 10° C. perminute to 230° C. followed by holding at this temperature for 10minutes, then 10° C. per minute to 250° C. followed by holding at thistemperature for 10 minutes. Completion of a second scan using theaforementioned conditions revealed no events up to a sharp exothermicrise with an onset at 265.2° C. EXAMPLE 4

A. Synthesis of 1,4-bis(4-methoxybenzoyl)hydrazide

4-Methoxybenzoyl chloride (75.0 gram, 0.44 mole) is dissolved intetrahydrofuran (750 milliliters) then added to an addition funnel whilemaintained under a nitrogen atmosphere. Tetrahydrofuran (500milliliters) and triethylamine (52.27 gram, 0.517 mole) are added to atwo liter glass reactor equipped with a condenser, stirring, a nitrogeninlet, an inlet covered by a rubber septum, the reactant-containingaddition funnel and a thermometer. Anhydrous hydrazine (6.73 grams, 0.21mole) is added to the reactor via injection through the rubber septum.The reactor exterior is maintained in a methylene chloride bath,stirring commences under a nitrogen atomsphere and the reactants arecooled to 0° C. by addition of dry ice to the methylene chloride bath.Once the 0° C. temperature is established, the 4-methoxybenzoylchloride-tetrahydrofuran solution is added dropwise to the reactor overa one hour period and at a rate so as to maintain the 0° C. reactiontemperature. After completion of the addition, the slurry is stirred foran additional hour while maintaining the 0° C. temperature, followed byremoval of the cooling bath and gradual warming to room temperature (23°C.). After stirring for four hours at room temperature, the reactorcontents are filtered and the recovered crystals slurried in deionizedwater (100 milliliters) then recovered by filtration and dried undervacuum at 80° C. and 1 mm Hg to a constant weight of 28.83 grams ofbright white crystalline needles. A second crop of crystals (3.14 grams)are recovered by rotary evaporation of the filtrate to a volume of 500milliliters followed by cooling to room temperature, filtration anddrying under vacuum. Fourier transform infrared spectrophotometricanalysis of a potassium bromide pellet of the product reveals thepresence of secondary hydrazide N--H stretching (solid state) at 3207cm⁻¹, secondary hydrazide carbonyl stretching (solid state) at 1598 cm⁻¹(combined as a double peak with aromatic ring absorption at 1609 cm⁻¹),the methoxy group C--H stretching at 2837 cm⁻¹ and the out-of-plane C--Hbending vibration at 841 cm-1 indicative of para-disubstitution. Protonmagnetic resonance spectroscopy and ¹³ carbon magnetic resonancespectroscopy further substantiated the product structure. High pressureliquid chromatographic analysis using an ultraviolet absorbance detectorreveals a single peak comprising 99.1 area % (molar absorptivity notdetermined) of the product.

B. Synthesis of 2,5-(4-methoxyphenyl)oxadiazole

1,4-bis(4-Methoxybenzoyl)hydrazide (7.48 grams, 0.0249 mole) from Babove and phosphorous oxychloride (250 grams) are added to a one literglass reactor equipped with a glycol-water condenser chilled to 2° C.,stirring, a nitrogen inlet flowing at a rate of one liter per minute anda thermometer-heating mantle-temperature controller assembly. Heating toa 106° C. reflux commences and after 16 hours at the 106° C.temperature, a distillation head is added between the reactor and thecondenser and phosphorous oxychloride (200 milliliters) is thendistilled from the reactor into a receiver. The solution remaining inthe reactor is cooled to 50° C., then recovered and added to stirreddeionized water (2 liters). After stirring for five minutes, the whitecrystalline product is recovered via filtration, washed in the filterwith three 100 milliliter portions of deionized water, then dried undervacuum at 100° C. and 1 mm Hg to a constant weight of 6.76 grams.Fourier transform infrared spectrophotometric analysis of a potassiumbromide pellet of the product reveals the presence of absorptions at1609, 1589 (shoulder), 1490, 1437 and 1417 cm⁻¹ characteristic of thearomatic ring and the oxadiazole ring, the methoxy group C--H stretchingcentered at 2838 cm⁻¹ and the out-of-plane C--H bending vibration at 832cm⁻¹ indicative of para-disubstitution. High pressure liquidchromatographic analysis using an ultraviolet absorbance detectorreveals a single peak comprising 99.9 area % (molar absorptivity notdetermined) of the product.

C. Demethylation of 2,5-(4-methoxyphenyl)oxadiazole

2,5-(4-methoxyphenyl)oxadiazole (6.65 grams, 0.0471 methoxy equivalent),anhydrous lithium iodide (11.16 grams, 0.0834 mole) and2,4,6-trimethylpyridine (35 milliliters) are added to a one liter glassreactor equipped with a glycol-water condenser chilled to 2° C.,stirring, a nitrogen inlet flowing at a rate of one liter per minute anda thermometer-heating mantle-temperature controller assembly. Thelithium iodide used was dried under vacuum at 175° C. and 1 mm Hg for 16hours immediately prior to use herein. Heating and stirring of theslurry under a nitrogen atmosphere commences and once the temperatureachieves 148° C., a solution forms. After an additional eight minutes ofheating, a 170° C. reflux is achieved and the solution becomes hazy.After five minutes at reflux, crystals began to deposit on the walls ofthe reactor. After a total of 318 minutes at reflux (170° to 167° C.),the stirred crystalline slurry is cooled to 50° C., then dissolved indeionized water (100 milliliters). Once the solution is cooled to roomtemperature (23° C.), stirring of the solution commences, thenconcentrated aqueous hydrochloric acid (50 milliliters) is added. Afterstirring for two minutes, the white crystalline product is recovered viafiltration, washed in the filter with three 100 milliliter portions ofdeionized water, then dried under vacuum at 80° C. and 1 mm Hg to aconstant weight of 5.69 grams. Fourier transform infraredspectrophotometric analysis of a potassium bromide pellet of the productreveals the presence of absorptions at 1609, 1589 (shoulder), 1570(shoulder), 1497, and 1437 cm⁻¹ characteristic of the aromatic ring andthe oxadiazole ring, the hydroxyl group O--H stretching centered at 3163cm-1 and the out-of-plane C--H bending vibration at 837 cm⁻¹ indicativeof para-disubstitution. Differential calorimetry scanning calorimetry ofa portion of the product (10.3 milligrams) heated at 10° C. per minuteunder nitrogen flowing at 35 cubic centimeters per minute reveals asharp melting point endotherm (87.0 joules per gram) with a minimum at349.2° C.

D. Epoxidation of 2,5-(4-hydroxyphenyl) oxadiazole

2,5-(4-Hydroxyphenyl)oxadiazole (5.60 grams, 0.0441 hydroxyl equivalent)from A above, epichlorohydrin (407.7 grams, 4.4 moles) andtetrabutylammonium bromide (0.056 gram, 1.00% wt. of the diphenolreactant used) are added to a one liter glass round bottom reactor andheated to 75° C. with magnetically driven stirring under a nitrogenatmosphere flowing at a rate of one liter per minute. The slurry becomesa clear solution after 428 minutes at the 75° C. reaction temperature.After 652 minutes at 75° C., high pressure liquid chromatographicanalysis of a portion of the light amber colored solution demonstratesthat complete conversion of the diphenol has occurred. At this time, awater separator is interspersed between the reactor and the chilled(-2.5° C.) glycol condenser and an addition funnel containing sodiumhydroxide (1.98 grams, 0.0496 mole) dissolved in deionized (2.42 grams,55% wt. of the solution) and a vacuum line are added to the reactor. Thenitrogen purge is shut off simultaneous with initiation of the vacuum.The vacuum and reaction temperature are equilibrated at 70 mm Hg and 50°C., respectively and such that a vigorous reflux is maintained withcontinuous return of dry epichlorohydrin from the water separator to thereactor. After equilibration, dropwise addition of the aqueous sodiumhydroxide commences. After 53 minutes, addition of the aqueous sodiumhydroxide is complete. After an additional 2.75 hours at the 70 mm Hgvacuum and 50° C. reaction temperature, heating ceases, vacuum isreleased and the product slurry recovered. The recovered slurry isfiltered through a bed of diatomaceous earth while still hot and theresultant light amber colored solution is then washed in a separatoryfunnel with deionized water (100 milliliters), dried over anhydroussodium sulfate, then filtered. The recovered filtrate is rotaryevaporated under a vacuum with heating to 90° C. The resultant powder isdried in a vacuum oven at 80° C. and 1 mm Hg to provide a constantweight of 5.51 grams of white crystalline product. Titration of aportion of the product reveals an epoxide equivalent weight of 187.4.Fourier transform infrared spectrophotometric analysis of a potassiumbromide pellet of the product reveals the presence of absorptions at1609, 1589 (shoulder), 1497, 1457, 1430 and 1423 (double peak) cm⁻¹characteristic of the aromatic ring and the oxadiazole ringdisappearance of the hydroxyl group O--H stretching centered at 3163cm⁻¹, out-of-plane C--H bending vibration at 839 cm⁻¹ indicative ofpara-disubstitution and epoxide --C--O-- stretching absorbance at 866and 912 cm⁻¹. Differential scanning calorimetry scanning calorimetry ofa portion of the product (13.0 milligrams) heated from 30° to 300° C. at10° C. per minute under nitrogen flowing at 35 cubic centimeters perminute reveals a sharp melting point endotherm (128.7 joules per gram)with a minimum at 200.1° C. followed by an exotherm (370.0 joules pergram) with a maximum at 253.6° C. High pressure liquid chromatographicanalysis using an ultraviolet absorbance detector reveals a single peakcomprising 93.3 area % (molar absorptivity not determined) of theproduct, with the balance of the area contained in a single additionalcoproduct peak.

E. Characterization of the Diglycidyl Ether of2,5-(4-hydroxyphenyl)oxadiazole for Liquid Crystallinity

Analysis of a portion of the diglycidyl ether of2,5-(4-hydroxyphenyl)oxadiazole from D above via crosspolarized lightmicroscopy is completed using a microscope equipped with a programmablehot stage with heating from 30° to 243° C. using a heating rate of 10°C. per minute. The results are reported in Table IV.

                  TABLE IV                                                        ______________________________________                                        OBSERVED                                                                      TRANSITION                                                                    TEMPERATURE (°C.)                                                                    COMMENTS                                                        ______________________________________                                         30           Birefringent, crystalline solid.                                187           First fluidity noted.                                           190           Nematic liquid crystal fluid forms.                             195           Isotropization.                                                 225           Viscosity increases, opalescent fluid due                                     to grainy birefringent microdomains                                           forming.                                                        243           Thermosets to opalescent solid with                                           grainy birefringent microdomains.                               ______________________________________                                    

The diglycidyl ether is an enantiotropic liquid crystal.

EXAMPLE 5 Preparation of a Blend of the Diglycidyl Ether of 2,5-(4-Hydroxyphenl)oxadiazole and 2,5-(4-Hydroxyphenyl)oxadiazole andCopolymerization

A portion (0.1131 gram, 0.0006 epoxide equivalent) of the diglycidylether of 2,5-(4-hydroxyphenyl)oxadiazole from Example 4-D and a portion(0.0767 gram, 0.0006 hydroxyl equivalent) of2,5-(4-hydroxyphenyl)oxadiazole from Example 4-C are added to a ceramicmortar and ground to a homogeneous powder. Differential scanningcalorimetry analysis of a portion (9.60 milligrams) of the powder blendheated at 10° C. per minute under nitrogen flowing at 35 cubiccentimeters per minute revealed an exotherm with multiple shoulders(103.5 joules per gram) and with a maximum at 197.6° C. A sharpexothermic rise with an onset at 267.5° C. is observed at the completionof the first exothermic event. Analysis of a portion of the powder blendvia crosspolarized light microscopy is completed using a microscopeequipped with a programmable hot stage preheated to 200° C. The resultsare reported in Table V.

                  TABLE V                                                         ______________________________________                                        TIME                                                                          at 200° C. (sec.)                                                                   COMMENTS                                                         ______________________________________                                        12           First fluidity noted.                                            14           Flows to a nematic liquid crystal                                             fluid, some dispersed crystals present.                          22           Fuses to a solid with nematic liquid                                          crystal texture, highly birefringent.                            ______________________________________                                    

EXAMPLE 6 Analysis of Copolymerized Blend of Diglycidyl Ether of2,5-(4-Hydroxyphenyl)oxadiazole and 2,5-(4 -Hydroxyphenyl)oxadiazole forGlass Transition Temperature

A portion (12.55 milligrams) gram of the diglycidyl ether of2,5-(4-hydroxyphenyl)oxadiazole and 2,5-(4-hydroxyphenyl)oxadiazoleblend from Example 5 are cured in a differential scanning calorimeter byheating at 10° C. per minute under a stream of nitrogen flowing at 35cubic centimeters per minute to 220° C., followed by holding at thistemperature for 20 minutes. After gradual cooling to 30° C., a secondscan is completed by heating from 30° to 250° C. at 10° C. per minuteunder nitrogen flowing at 35 cubic centimeters per minute. No eventswere detected up to a sharp exothermic rise with an onset at 238.6° C.

EXAMPLE 7 A. Synthesis of 2,5-(3-hydroxyphenyl)thiadiazole

p-Hydroxybenzaldehyde (24.99 grams, 0.205 mole), sulfur (13.14 grams,0.41 mole), and ethylene glycol (300 milliters) are added to a one halfliter glass reactor equipped with a condenser venting through a scrubbercharged with aqueous sodium hydroxide solution, stirring, a nitrogeninlet flowing at a rate of one liter per minute, an addition funnel anda thermometer-heating mantle-temperature controller assembly. Hydrazinemonohydrate (30.79 grams, 0.615 mole) is added dropwise to the reactor,followed by an aliquot of additional ethylene glycol (100 milliliters).After completion of the addition, heating to 105° C. commences with thereaction temperature initially overshooting to 120° C. After 65 hours atthe 105° C. temperature, a slurry of crystals are observed in thereactor. The reaction mixture is cooled and the crystals allowed tosettle, then recovered via filtration. The recovered crystals are addedto a beaker and slurried in a minimum of cold (0° C.) ethanol and thenrefiltered. The crystals are recovered by filtration, reslurried in coldethanol, then recovered by filtration and dried under vacuum at 80° C.and 1 mm Hg to a constant weight of 16.82 grams of pale yellow coloredproduct. Fourier transform infrared spectrophotometric analysis of apotassium bromide pellet of the product reveals the presence ofabsorptions at 1609 (shoulder), 1589, 1530 (minor shoulder), 1497(shoulder), 1463 (shoulder), 1443, 1423 (shoulder), and 1370 cm⁻¹characteristic of the aromatic ring and the thiadiazole ring, thehydroxyl group O--H stretching centered at 1382 cm⁻¹ and theout-of-plane C--H bending vibration at 773 cm⁻¹ indicative ofmeta-disubstitution. Differential scanning calorimetry of a portion ofthe product (14.8 milligrams) heated at 10° C. per minute under nitrogenflowing at 35 cubic centimeters per minute reveals a sharp melting pointendotherm (165.9 joules per gram) with a minimum at 286.2° C. Protonmagnetic resonance spectroscopy and 13carbon magnetic resonancespectroscopy further substantiated the product structure. High pressureliquid chromatographic analysis using an ultraviolet absorbance detectorreveals a single peak comprising 100 area % (molar absorptivity notdetermined) of the product.

B. Epoxidation of 2,5-(3-hydroxyphenyl)thiadiazole

2,5-(3-Hydroxyphenyl)thiadiazole (4.05 grams, 0.03 hydroxyl equivalent)from A above, epichlorohydrin (277.6 grams, 3.0 moles) andtetrabutylammonium bromide (0.0405 gram, 1.00% wt. of the diphenolreactant used) are added to a one liter glass round bottom reactor andheated to 75° C. with magnetically driven stirring under a nitrogenatmosphere flowing at a rate of one liter per minute. After 15 hours at75° C., high pressure liquid chromatographic analysis of a portion ofthe light amber colored solution demonstrates that complete conversionof the diphenol has occurred. At this time, a water separator isinterspersed between the reactor and the chilled (-2.5° C.) glycolcondenser and an addition funnel containing sodium hydroxide (1.35grams, 0.0338 mole) dissolved in deionized water (1.65 grams, 55% wt. ofthe solution) and a vacuum line are added to the reactor. The nitrogenpurge is shut off simultaneous with initiation of the vacuum. The vacuumand reaction temperature are equilibrated at 117 mm Hg and 50° C.,respectively and such that a vigorous reflux is maintained withcontinuous return of dry epichlorohydrin from the water separator to thereactor. After equilibration (5 minutes), dropwise addition of theaqueous sodium hydroxide commences. After 28 minutes, addition of theaqueous sodium hydroxide is complete. After an additional 2.5 hours atthe 117 mm Hg vacuum and 50° C. reaction temperature, heating ceases,vacuum is released and the product slurry recovered. The recoveredslurry is filtered through a bed of diatomaceous earth while still hotand the resultant light yellow colored solution rotary evaporated undera vacuum with heating to 90° C. The resultant solid product is allowedto cool to room temperature (23° C.), then suspended in acetone (40milliliters) with mixing until a fine slurry forms. Deionized water (20milliliters) is added to the slurry with mixing followed by filtration.The product removed by filtration is resuspended in acetone (40milliliters) with mixing, diluted with deionized water (20 milliliters),then filtered, followed by drying of the product recoverd on the filterin a vacuum oven at 80° C. and 1 mm Hg to provide a constant weight of5.29 grams of pale tan colored crystalline product. Titration of aportion of the product reveals an epoxide equivalent weight of 220.5(corrected for titrated contribution of the thiadiazole ring). Fouriertransform infrared spectrophotometric analysis of a potassium bromidepellet of the product reveals the presence of absorptions at 1609(shoulder), 1583, 1503 (shoulder), 1470, 1450 (shoulder), 1430, and 1370(shoulder) cm⁻¹ characteristic of the aromatic ring and the thiadiazolering, disappearance of the hydroxyl group O--H stretching centered at3382 cm-1, out-of-plane C--H bending vibration at 773 cm⁻¹ indicative ofmeta-disubstitution and epoxide --C--O-- stretching absorbance at 859and 919 cm⁻¹. Differential scanning calorimetry scanning calorimetry ofa portion of the product (11.1 milligrams) heated from 30° to 300° C. at10° C. per minute under nitrogen flowing at 35 cubic centimeters perminute reveals a melting point endotherm (64.7 joules per gram) with aminimum at 112.3° C. followed by an exotherm (495.3 joules per gram)with a maximum at 234.8° C.

EXAMPLE 8 Preparation of a Blend of the Diglycidyl Ether of2,5-(3-Hydroxyphenyl)thiadiazole and 4,4'-Diaminodiphenylsulfone

A portion (0.3538 gram, 0.0016 epoxide equivalent) of the diglycidylether of 2,5-(3-hydroxyphenyl)thiadiazole from Example 7-B and4,4'-diaminodiphenylsulfone (0.0996 gram, 0.0016 --NH equivalent) aredissolved in methylene chloride (5 milliliters) then dried in a forcedair, convection type oven at 50° C. Differential scanning calorimetryanalysis of a portion (10.6 milligrams) of the powder blend heated at10° C. per minute under nitrogen flowing at 35 cubic centimeters perminute reveals a melting point endotherm (45.7 joules per gram) with aminimum at 95.6° C. followed by an exotherm (343.8 joules per gram) witha maximum at 203.4° C.

What is claimed is:
 1. An epoxy resin containing an average of more thanone vicinal epoxide group per molecule and at least one thiadiazole oroxadiazole or both at least one thiadiazole and at least one oxadiazolegroup per molecule, said epoxy resin being represented by the followingFormula II:Formula II

    G--Z--Ar--(X.sup.1).sub.n --Z'--(X.sup.1).sub.n --(Ar--(X.sup.1).sub.n --Z'--(X.sup.1).sub.n).sub.n.sup.1 --Ar--Z--G

wherein each Z is independently a --O--, --S--, --NR--, --N< or --COO--group; G is ##STR12## J is hydrogen or a hydrocarbyl group having fromone to about 4, carbon atom(s); each Z'-- is independently a ##STR13##each Ar is independently a ##STR14## each X¹ is independently a --O--,--S--, --SO--, --SO₂ --, --CO--, --O--CO--, --CO--O--, --S--CO--,--CO--S--, --NR--CO--, --CO--NR--, --NR--CO--NH--, --NH--CO--NR--,--NH--CO--O-- or --O--CO--NH-- group; each R is independently hydrogenor a hydrocarbyl group having from one to about 10, carbon atoms; each Yis independently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom one to about 10, carbon atoms, a halogen atom, a nitro group, anitrile group, a --CO--R group or a --CO--OR group; A is a divalenthydrocarbyl group having from one to about 10, carbon atoms and canoptionally contain one or more heteroatoms selected from N, O, or S;each n independently has a value of zero or one and n¹ has a value ofzero to about
 10. 2. An epoxy resin of claim 1 wherein said thiadiazole,oxadiazole or both a thiadiazole and an oxadiazole group areincorporated so as to form a mesogenic moiety.
 3. The diglycidyl etherof 2,5-(4-hydroxyphenyl)thiadiazole, the diglycidyl ether of2,5-(4-hydroxyphenyl)oxadiazole or the diglycidyl ether of2,5-(3-hydroxyphenyl)thiadiazole.
 4. A blend comprising(A) at least oneepoxy resin containing an average of more than one vicinal epoxide groupper molecule and at least one thiadiazole, oxadiazole or both at leastone thiadiazole and at least one oxadiazole moiety per molecule saidepoxy resin being represented by the following Formula II:Formula II

    G--Z--Ar--(X.sup.1).sub.n --Z'--(X.sup.1).sub.n --(Ar--(X.sup.1).sub.n --Z'--(X.sup.1).sub.n).sub.n.sup.1 --Ar--Z--G

wherein each Z is independently a --O--, --S--, --NR--, --N< or --COO--group; G is ##STR15## J is hydrogen or a hydrocarbyl group having fromone to about 4, carbon atom(s); each Z'-- is independently a ##STR16##each Ar is independently a ##STR17## each X¹ is independently a --O--,--S--, --SO--, --SO₂ --, --CO--, --O--CO--, --CO--O--, --SCO--,--CO--S--, --NR--CO--, --CO--NR--, --NR--CO--NH--, --NH--CO--NR--,--NH--CO--O-- or --O--CO--NH-- group; each R is independently hydrogenor a hydrocarbyl group having from one to about 10, carbon atoms; each Yis independently hydrogen, a hydrocarbyl or hydrocarbyloxy group havingfrom one to about 10, carbon atoms, a halogen atom, a nitro group, anitrile group, a --CO--R group or a --CO--OR group; A is a divalenthydrocarbyl group having from one to about 10, carbon atoms and canoptionally contain one or more heteroatoms selected from N, O, or S;each n independently has a value of zero or one and n¹ has a value ofzero to about 10 and (B) at least one epoxy resin containing an averageof more than one vicinal epoxide group per molecule which is differentfrom the epoxy resin of component (A).